1. Field of the Invention
The present invention relates to an automatic performance apparatus that can change the performance duration of a piece of music.
2. Prior Art
An automatic performance apparatus which stores performance data of a piece of music into a performance data memory, and automatically performs the piece by sequentially reading the data from the memory, has been developed.
Among these types of automatic performance apparatuses, there are some that can shorten or lengthen the performance duration of a piece: for example, "Model 4050 Autolocator/performance-duration-and-tempo-management sequencer" of Fostex Cooperation in Japan is known. These types of automatic performance apparatuses are used for performing pieces of predetermined duration, for instance, sound track music of a cinema film or commercial music on TV which are connected with visual images.
In the sound track music, a piece of music is divided into a number of performance sections, and these sections are successively assigned to consecutive scenes of a film so that the scenes and the music are synchronized. Generally speaking, the total duration of scenes and that of music do not match, and hence, the performance duration must be adjusted.
The conventional automatic performance apparatus mentioned above, however, adjusts the performance duration only by uniformly regulating the reproduction speed of the piece as shown in FIG. 1A. In FIG. 1A, for example, the former performance duration Ta1 and the latter performance duration Tb1 are uniformly shortened to duration Ta2 and duration Tb2, respectively. Thus, the conventional apparatus can only uniformly shorten or lengthen the performance sections. Consequently, duration adjustment as shown in FIG. 1B is impossible: the duration adjustment, in which the duration Ta1 of the former performance section assigned to one scene is maintained Ta1, while the duration Tb1 of the latter performance section is shortened to Tb2 so that the total duration is matched to the desired duration, is difficult. When the adjustment shown in FIG. 1B is inevitable, the reproduction speed must be changed by external operation during the performance. The operation, however, is very difficult and cannot achieve the adjustment of the total performance duration.
The adjustment in a manner shown in FIG. 1B is also required in the following case: the alteration of the tempo of a piece sometimes changes the expression or image of the piece; and some sections may have more impact than others, giving a disharmonious feeling to the audience, while other sections scarcely affect the image when the performance speed thereof is changed. Hence, it is desired that the tempo of the sections which scarcely affect the image of the piece is modified, while the tempo of the other sections is maintained The adjustment shown in FIG. 1B can be applied in such a case.